The present invention relates to a curable copolymer, and more particularly to a vinyl curable copolymer having a hydrolyzable silyl group at the molecular ends or side chains, having excellent flexibility, solvent resistance and adhesion to organic materials, and a process for preparing the same.
Japanese Unexamined Patent Publication No. 36395/1979 discloses that a hydrolyzable silyl group-containing vinyl resin is excellent in curability at ordinary temperature, adhesion to inorganic materials such as concrete, glass, a steel plate and aluminum, and weatherability. However, the hydrolyzable silyl group-containing vinyl resin is unsatisfactory in flexibility, solvent resistance and adhesion to organic materials.
It is desired to improve the above-mentioned properties, i.e. flexibility, solvent resistance and adhesion to organic materials in the art of, for instance, an automotive refinishing paint.
In order to improve the flexibility, it is proposed to add a plasticizer such as butyl benzyl phthalate or a hydrolyzable silyl group-containing resin whose main chain is a flexible chain such as polyether or polyester to the vinyl resin. However, the flexibility can be improved, but the solvent resistance tends to lower.
It is disclosed in U.S. Pat. No. 3,632,557 (Brode et al) that a silyl group-containing polyester resin having N,N-disubstituted urea bond in its main chain is added to the vinyl resin. In such a case, both the flexibility and the solvent resistance can be improved since the N,N-disubstituted urea bond is large in the cohesion. However, the polyester resin is poor in compatibility with the silyl group-containing vinyl resin.
As aforementioned, it is difficult to improve both the flexibility and the solvent resistance of the hydrolyzable silyl group-containing vinyl resin by blending other components with the vinyl polymer.
Also, as a method for introducing a urethane bond having large cohesion into the silyl group-containing vinyl resin, for example, U.S. Pat. No. 4,491,650 (Rizk et al) discloses a coating resin obtained by reacting a polyacrylate or polymethacrylate havig an alcoholic hydroxyl group with an isocyanate silane. However, since the above coating resin does not have an ingredient capable of giving the flexibility such as polyether, polyester or polysiloxane in its molecule, the flexibility cannot be remarkably improved.
An object of the present invention is to provide a hydrolyzable silyl group-containing vinyl resin having excellent flexibility, solvent resistance and adhesion to organic materials.
A further object of the present invention is to provide a process for the preparation of the hydrolyzable silyl group-containing vinyl resin.
These and other objects of the present invention will become apparent from the following description.